From b9f0e6923d645a044f837d61a9343ea16d56504e Mon Sep 17 00:00:00 2001 From: David Bremner Date: Mon, 25 Nov 2013 22:55:24 -0400 Subject: util: detect byte order Unfortunately old versions of GCC and clang do not provide byte order macros, so we re-invent them. If UTIL_BYTE_ORDER is not defined or defined to 0, we fall back to macros supported by recent versions of GCC and clang --- util/endian-util.h | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 util/endian-util.h (limited to 'util/endian-util.h') diff --git a/util/endian-util.h b/util/endian-util.h new file mode 100644 index 00000000..bc80c40b --- /dev/null +++ b/util/endian-util.h @@ -0,0 +1,38 @@ +/* this file mimics the macros present in recent GCC and CLANG */ + +#ifndef _ENDIAN_UTIL_H +#define _ENDIAN_UTIL_H + +/* This are prefixed with UTIL to avoid collisions + * + * You can use something like the following to define UTIL_BYTE_ORDER + * in a configure script. + */ +#if 0 +#include +#include +uint32_t test = 0x34333231; +int main() { printf("%.4s\n", (const char*)&test); return 0; } +#endif + +#define UTIL_ORDER_BIG_ENDIAN 4321 +#define UTIL_ORDER_LITTLE_ENDIAN 1234 + + +#if !defined(UTIL_BYTE_ORDER) || ((UTIL_BYTE_ORDER != UTIL_ORDER_BIG_ENDIAN) && \ + (UTIL_BYTE_ORDER != UTIL_ORDER_LITTLE_ENDIAN)) +#undef UTIL_BYTE_ORDER +#ifdef __BYTE_ORDER__ +# if (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) +# define UTIL_BYTE_ORDER UTIL_ORDER_LITTLE_ENDIAN +# elif (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__) +# define UTIL_BYTE_ORDER UTIL_ORDER_BIG_ENDIAN +# else +# error "Unsupported __BYTE_ORDER__" +# endif +#else +# error "UTIL_BYTE_ORDER not correctly defined and __BYTE_ORDER__ not defined." +#endif +#endif + +#endif -- cgit v1.2.3